Lower thread regulator for automatic sewing and embroidering machines



March 8, 1966 H. ROLAUFFS 3,238,907

LOWER THREAD REGULATOR FOR AUTOMATIC SEWING AND EMBROIDERING MACHINES 2 Sheets-Sheet 1 Filed July 29, 1965 March 8, 1966 RQLAUFFS 3,238,907

LOWER THREAD REGULATOR FOR AUTOMATIC SEWING AND EMBROIDERING MACHINES Filed July '29, 1963 2 Sheets-Sheet 2 United States Patent 3,238,907 LOWER THREAD REGULATOR FOR AUTOMATIC SEWING AND EMBROIDERING MACHINES Hans Rolaulfs, Krefeld, Germany, assignor to Maschinenfabrik Carl Zangs Aktien-Gesellschaft, Krefeld, Germany Filed July 29, 1963, Ser. No. 298,030 Claims priority, application Germany, Aug. 7, 1962, M 42,121 3 Claims. (Cl. 112-217) The present invention relates to an improvement of heretofore known control devices for the lower thread of automatic sewing and embroidering machines in which, between the needle plate and the looper, there is provided a feeler hook for feeling the lower thread.

Heretofore known controls for feeling the lower thread comprise a spring for pressing the feeler hook against the lower thread when the needle moves upwardly, i.e. tightens the last formed stitch. At this instant, the lower thread is taut, and the feeler hook engaged by the spring is prevented by said lower thread from any further movement. The movable contact mechanically connected to the feeler hook is in this way prevented from contacting the counter-contact arranged stationarily on the machine frame. A small cam disc controls the timed feeling of the lower thread. This cam disc is mounted on the rotated looper shaft and by means of a lever holds the feeler hook against the thrust of the spring away from the working range of the needle until the stitch has been tightened and the feeling operation may be effected.

In case of a break of the lower thread or the absence of the lower thread in view of a bobbin being empty, the feeler hook will, when carrying out its feeling operation, not encounter any resistance, so that it will move on, and the movable electric contact connected thereto will contact the stationary counter-contact. In this way, the circuit will be closed, and the machine is electrically turned off.

In view of the considerable accumulation of dust and fluff below the needle and in the neighborhood of the looper, heretofore known lower thread control devices are liable to frequent disturbances because the contacts are soiled by dust and fluff, whereby a poor contact will frequently result. Moreover, also frequently soiling of the pressing spring for the feeler hook causes disturbances.

It is, therefore, an object of the present invention to provide control means which will overcome the abovementioned drawbacks.

It is another object of this invention so to arrange the spring means for the spring actuated contact means that a soiling of the spring means will be prevented, at least to a major extent.

It is still another object of this invention to replace the heretofore employed spring means for the contact members by a simplified spring means.

Still another object of this invention consists in so designing the lower thread control that it may be employed also with sewing and embroidering automats built prior to the present invention.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIGURES l and 2 represent perspective views of an arrangement according to the present invention respectively showing the control cam disc in defferent positions during the feeling operation;

FIGURE 3 is a perspective view similar to those of FIGURES 1 and 2 but showing the device with a thread in broken condition;

FIGURE 4 illustrates partly in top view and partly in section the arrangement according to the present invention.

The arrangement according to the present invention is characterized primarily in that the electric spring contacts which are actuated when a thread break occurs or the thread supply is interrupted, are arranged in a closed switch housing while the spring-urged control member or striker engages a leaf-spring operable to actuate the feeler hook. In this way, the lower thread control device is greatly simplified, while disorders due to soiling of the heretofore employed coil spring will be eliminated.

The lower thread control according to the present invention may also, without difficulties, be employed with heretofore designed sewing and embroidering automats while the heretofore employed pressing springs and open contacts will become superfluous.

Referring now to the drawing in detail, the arrangement shown therein comprises a lower thread control formed by a feeler hook keyed to a shaft 9. This shaft may he journalled in any convenient manner, for instance, in a bearing block 16 indicated in dot-dash line in FIGS. 1 and 3 and shown in solid line in FIGS. 2 and 4. Shaft 9 has furthermore keyed thereto a lever 5 having its free end in FIG. 1 engaging a cam disc 6. The free end of the feeler hook 1 rests against the lower thread 8 as shown in FIG. 2 when, by means of the needle 7 the stitch is tightened and the lower thread 8 is taut. As will be particularly evident from FIG. 4, the feeler hook I is pressed against the lower thread 8 by a leaf-spring 2. Leaf-spring 2 is mounted in any convenient manner, for instance, by a rivet, on a switch housing 3 which normally engages a control striker 10 which in its turn extends from the outside through an opening 3a into a closed housing 3. Arranged within said housing is a leaf-spring 17 connected to said housing 3 in any con venient manner, for instance, by a bolt 18. Said leafspring 17, which has an outwardly extending lead 17a for connection with the electric control circuit of the automat, carries two contacts 15 and 15a for respective engagement with counter-contacts 19 and 19a likewise arranged within the housing 3 and respectively connected to leads 2% and Zila for connection with the electric control circuit of the device. Connected to leaf-spring 17 is one end of a coil spring 21 the other end of which is connected to a leaf spring 22 engaging control striker 19. As will be evident from the above, when the automat is in normal operation, the feeler hook I is prevented by lower thread 8 from tilting in the direction of the arrow 4 (FIG. 2) so that the various elements of the control device according to the invention occupy the position shown in FIG. 4 in which contact 15a engages counter-contact 19a.

It will be appreciated from the drawing that cam disc 6 has a circular cam surface 6a and a cam surface 6b of special contour. When the needle 7 moves in downward direction, there is no thread 8 which can hold loop hook 1 back, i.e., can prevent hook 1 from moving in the direction of the arrow 4. It is, therefore, necessary that other means are provided during this stage of operation to hold loop 1 back. This is done by the cam surface 6a in cooperation with the lever end 5. In other words, when the needle moves downwardly, lever end 5 slides on cam surface 6a. On the other hand, when needle 7 moves upwardly, it is desired that thread 8 holds hook I back so that when thread 8 breaks, the control arrangement according to the present invention will be able to become effective by movement of hook I in the direction of the arrow 4. Therefore, during the normal upward movement of needle 7, lever end 5 is free from cam disc 6, i.e., is spaced from the cam contour 6b, as shown in FIG. 2.

When the thread breaks, as indicated in FIG. 3 or the lower thread supply bobbin becomes empty, the feeler book 1 will in the corresponding position of cam disk 6 be no longer prevented from moving in the direction of the arrow 4 (FIG. 3). Consequently, when feeler hook 1 moves upwardly leaf-spring 2 will follow said feeler hook 1 so that it no longer pushes control striker 10 downwardly. Coil spring 21 in cooperation with leafspring 22 will then push striker 10 upwardly, and, due to this movement and in particular due to the expansion of spring 21, leaf-spring 17 will now instantaneously move upwardly thereby causing its contact to engage the counter-contact 19 as a result of which a circuit is closed between lead 17a and lead 20a, which circuit brings the automat to a stand-still, e.g., by actuating a brake (not shown).

The lower thread control according to the present invention is in a manner known per se arranged between a needle plate 13 (FIG. 1) and a looper 14. These two parts are indicated in dot-dash line in FIG. 1. The looper shaft 12 to which the looper 14 is connected for rotation therewith may be journalled in any convenient manner.

It is understood that the lower thread is fed from a lower thread supply means, such as a bobbin, while the looper is positioned between the supply means and the needle, at least while the latter is in an upper position. The looper actuating means in the form of shaft 12, operates the looper in timed relation to the up and down movement of the needle and thus also controls the feeler so that a feeling operation is carried out thereby only during an upward movement of the needle.

It is, of course to be understood that the present invention is, by no means, limited to the particular construction shown in the drawings, but also comprises any modifications within the scope of the appended claim.

What I claim is:

'1. In combination, a sewing machine and automatic embroidering machine having an alternately upwardly and downwardly moving needle and also having lower thread supply means spaced from said needle and having a looper positioned between the lower thread supply means and the needle, a lower thread responsive control, which includes: a stationary housing, at least two contacts enclosed in said housing and engageable with each other to close an electric circuit for causing the machine to carry out its normal operation, a movably supported feeler engaging said lower thread above said looper, a leaf spring supported by said housing and engaging said feeler and continuously urging said feeler to move from a first position in which one of its ends is on one side of the path of movement of the lower thread to be felt by said feeler to a second position in which said one end of said feeler is on the opposite side of the path of movement of said lower thread to be felt, actuating means for actuating said looper in timed relation to the up and down movement of said needle, control means operatively connected to said actuating means and to said feeler and operable for preventing said feeler from moving from said first to said second position during the downward movement of said needle while releasing said feeler for movement to said second position during upward movement of said needle, said feeler also being adapted to be prevented by a lower thread picked up by said needle from moving from said first position to said second position while said needle is moving upwardly, and means directly interpos'ed between said leaf spring and said contacts and operable in response to said feeler failing to encounter any lower thread resistance during the upward movement of said needle to break the contact engagement between said contacts to thereby interrupt said circuit and bring the machine to a standstill.

2. An arrangement according to claim 1, in which said last mentioned means interposed between said leaf spring and said contacts includes spring means supporting one of said contacts and urging said one of said contacts away from the other contact and also includes means interposed and in engagement with said leaf spring and said spring means for preventing said spring means from breaking the contact engagement between said contacts as long as said feeler is in its first position.

3. An arrangement according to claim 2, in which a third contact is provided in said housing so positioned as to be engaged by said one of said contacts when said feeler moves to its said second position thereby providing means for actuating a brake mechanism for quickly halting the machine.

References Cited by the Examiner UNITED STATES PATENTS 1,367,219 2/1921 Weis 11 22l9 1,742,953 1/1930 Gahlert et al. 112 219 2,868,151 1/1959 Winz 112219 3,101,687 8/1963 Zeltwanger -a 112--219 ROBERT V. SLOAN, Primary Examiner. 

1. IN COMBINATION, A SEWING MACHINE AND AUTOMATIC EMBROIDERING MACHINE HAVING AN ALTERNATELY UPWARDLY AND DOWNWARDLY MOVING NEEDLE AND ALSO HAVING LOWER THREAD SUPPLY MEANS SPACED FROM SAID NEEDLE AND HAVING A LOOPER POSITIONED BETWEEN THE LOWER THREAD SUPPLY MEANS AND THE NEEDLE, A LOWER THREAD RESPONSIVE CONTROL, WHICH INCLUDES; A STATIONARY HOUSING, AT LEAST TWO CONTACTS ENCLOSED IN SAID HOUSING AND ENGAGEABLE WITH EACH OTHER TO CLOSE AN ELECTRIC CIRCUIT FOR CAUSING THE MACHINE TO CARRY OUT ITS NORMAL LOWER THREAD ABOVE SAID SUPPORTED FEELER ENGAGING SAID LOWER THREAD ABOVE SAID LOOPER, A LEAF SPRING SUPPORTED BY SAID HOUSING AND ENGAGING SAID FEELER AND CONTINUOUSLY URGING SAID FEELER TO MOVE FROM A FIRST POSITION IN WHICH ONE OF ITS ENDS IS ON ONE SIDE OF THE PATH OF MOVEMENT OF THE LOWER THREAD TO BE FELT BY SAID FEELER TO A SECOND POSITION IN WHICH SAID ONE END OF SAID FEELER IS ON THE OPPOSITE SIDE OF THE PATH OF MOVEMENT OF SAID LOWER THREAD TO BE FELT, ACTUATING MEANS FOR ACTUATING SAID LOOPER IN TIMED RELATION TO THE UP AND DOWN MOVEMENT OF SAID NEEDLE, CONTROL MEANS OPERATIVELY CONNECTED TO SAID ACTUATING MEANS AND TO SAID FEELER AND OPERABLE FOR PREVENTING SAID FEELER FROM MOVING FROM SAID FIRST TO SAID SECOND POSITION DURING THE DOWNWARD MOVEMENT OF SAID NEEDLE WHILE RELEASING SAID FEELER MOVEMENT TO SAID SECOND POSITION DURING UPWARD MOVEMENT OF SAID NEEDLE, SAID FEELER ALSO BEING ADAPTED TO BE PREVENTED BY A LOWER THREAD PICKED UP BY SAID NEEDLE FROM MOVING FROM SAID FIRST POSITION TO SAID SECOND POSITION WHILE SAID NEEDLE IS MOVING UPWARDLY, AND MEANS DIRECTLY INTERPOSED BETWEEN SAID LEAF SPRING AND SAID CONTACTS AND OPERABLE IN RESPONSE TO SAID FEELER FAILING TO ENCOUNTER ANY LOWER THREAD RESISTANCE DURING THE UPWARD MOVEMENT OF SAID NEEDLE TO BREAK THE CONTACT ENGAGEMENT BETWEEN SAID CONTACTS TO THEREBY INTERRUPT SAID CIRCUIT AND BRING THE MACHINE TO A STANDSTILL. 